GB753153A - Improvements in or relating to continuously operated gas-fired furnaces - Google Patents

Abstract

753,153. Continuous metal-heating furnaces. WISTRA OFENBAUGES. March 3, 1954 [March 3, 1953], No. 6280/54. Classes 51(1) and 51(2). In a continuous metal-heating furnace of the pusher type divided into a preheating zone 3, a main heating zone 4, and an equalising zone 5, the latter is heated by burners 8 disposed in the direction of travel of the billets 1 and supplied with preheated fuel gas and with a highly preheated mixture of air and waste gases. The concave end wall of the equalising chamber causes the hot gases to double back over the billets, after which they traverse in turn, a duct 12, a brick recuperator 13, a duct 15 and a recuperator 9. A pipe 10 feeds hot fuel gas from the recuperator 9 to the burners 8, and also to main burners 7 disposed oppositely to the direction of travel of the billets. Hot air from the recuperator 9 passes through a branched pipe 11, partly to the main burners 7, and partly, after admixture with hot waste gases diverted from the duct 15 under control of a valve 16, to a fan 14, which forces the air/waste gases mixture through the recuperator 13 and a duct 19 to the burners 8. Billets in the preheating zone 3 are heated from above by waste gases from the main heating zone 4, and from below by burners 6 supplied with cold fuel gas and air. In a modification, Fig. 2 (not shown), the recuperator 13 is omitted and waste gases are caused to recirculate within the equalizing chamber by forming the burners 8 as Venturi injectors. A further modification, Fig. 3 (not shown), also omits the recuperator 13, and waste gases drawn off the preheating zone are supplied by a fan to the burners 8.